Air plasma waveguide using pico-sec and nano-sec laser pulses

We report a shock driven plasma in air breakdown using pump-probe to elucidate the hydrodynamic evolution of air plasma waveguide. Imaging of the evolution of air plasma plume is used to investigate the pump pulse effect on the plume dynamic. Imaging of the channeled pulse through evolved waveguide shows five time enhancement in Rayleigh length at 7 ns delay of probe pulse with respect to pump pulse. The evolved channel radius rch≈37μm has been shown to couple the maximum energy of the probe pulse yielding the electron density difference Δne~1018cm-3 between axis and periphery of the channel. The air plasma wave guide is shown to support the fundamental mode at optimum delay.